1. Fields of the invention
The present invention relates to joints assembled with driver bits, especially to joints with rings outside whose size range are recognized by different colors or words on the surface of the ring.
2. Descriptions of Related Art
Generally, a joint is formed by a polygonal prism connected with a cylinder. The polygonal prism is for mounting and connected with driver rods or power tools for rotating. A polygonal hole is arranged axially at a front end of the cylinder and a magnetic body is disposed on an inner end of the polygonal hole so as to replace different types of drivers bits.
Refer to U.S. Pat. No. 7,082,864 “Tool with protective sheath”, and U.S. Pat. No. 5,009,133 “Surface protective fastener tool”, the tools revealed are sleeves connected with drivers or the like such as joints. While applying a sheath to a tool, the sheath covers the whole tool and having at least one end thereof projecting slightly beyond an end of the tool. The sheath is fixed to the tool by an inwardly projecting rib in at least one end of the sheath engaged in an annular groove or channel in an surface of the tool so as to prevent the tool from sliding off the sheath and enable the sheath to rotate freely on the tool.
In another embodiment, when an extension of the sheath is coupled with a socket or other tools, the sheath completely covers the joint or connection between these tool parts. The opposite end of the sheath projects beyond the other end of the extension and an inwardly directed rib engages against the end of the extension to hold the sheath.
As revealed in U.S. Pat. No. 5,009,133, the protective fastener tool includes a lip that extends radially inward overlying one end of dual-end socket wrench so that both ends of the socket wrench are prevented from contacting and abrading an underlying surface.
A protective sheath for tools in prior arts mentioned above is to prevent marring of finished surfaces of the tool. A projection end of the sheath functions to contact the finished surface and prevent the tool (or the cylinder) from contacting the surface as it is rotated. The disadvantage of such design is in that: the sheath needs to cover the whole tool or cylinder so that the material used requires more and the cost is increased. Moreover, other machines are required to complete assembling of the sheath with the tool (or the cylinder). This is time-consuming and the cost is getting higher.
In order to help users get joints with correct size range while assembling different types of driver bits with various size ranges, a joint recognition member with improved structure is required.